1. Field of the Invention
The present invention is related to a motor driving apparatus, and more particularly related to a motor driving apparatus with soft-start and soft-lock start function, and an external Pulse Width Modulation (PWM) driving signal is transmitted through a soft-start unit to count the motor rotation signals so as to determine the output of the motor driving apparatus and achieve power-up soft-start function and soft-lock start function.
2. Description of the Prior Art
In recent years, personal computer (PC), portable computer/notebook (NB) or workstation are well development and the calculation speed of the micro chips (such as central unit processor (CPU) or digital signal processor (DSP)) are increased so fast. However, when the calculation speed of the micro chips is increased and the clock frequency is increased, there is lots of heat generated in the micro chips. The high temperature will result the following issues: the calculation malfunction of the microchip, and the influence of the circuits around the micro chips. Therefore, the thermal function of the micro chips is extremely significant technique.
Generally, the thermal method of the processing micro chips implements the conventional fans to solve the heat radiation. For example, the motor control driving device is used to turn on the fans to bring cooler air to the surface of the micro chips for heat radiation. However, the conventional method to drive the motor by the motor driving apparatus is required to generate the maximum torque to drive the motor so as to overcome the maximum torque limit. This kind of driving method won't cause any problems when the motor with low power. However, if the motor with high power or small internal resistances is used and the motor power is turned on by the maximum torque, a very large current is generated at the turn-on moment, as shown in FIG. 1a. After the power is turned on, the turn on voltage and the pulse width modulation signal are 100%, obviously, at this moment, the turn-on current is the largest and the noise is the largest. If the motor driving apparatus includes a current protect device, the motor driving apparatus won't be impacted by large current. If the motor driving apparatus doesn't include the current protect device, the motor driving apparatus will be destroyed at the moment when the power is turned on.
In addition, when the motor is in a lock condition because the irresistible external force of the motor or the inaccuracy of the motor, the motor driving apparatus will restart to drive the motor and confirm the irresistible external force is disappeared after a period of time. When the irresistible external force is disappeared, the motor will restart. At the same situation, in order to make sure the motor to restart, the maximum torque is used to drive the motor as the circumstance when the power is turned on. If the motor with high power or small internal resistances is used and the motor power is turned on by the maximum torque, a very large current is generated at the turn-on moment, as shown in FIG. 1b, and the motor driving apparatus would be destroyed when the motor is restarted.
In order to overcome the problem of the motor driving apparatus described above, there is a motor driving apparatus with a soft-start and soft lock-start function included in the present invention. An internal PWM control signal is used to count the motor rotation signal in the soft-start unit to determine the output of the motor driving apparatus so as to achieve soft-start and soft lock-start purposes.